1. Field of the Invention
The present invention relates to an improved recording method and apparatus suitable for forming images by jetting multi-color liquid in accordance with image signals in an ink jet recording system. More particularly, the present invention relates to a method and apparatus for forming a material used to record images repeatedly on a transfer medium in an ink jet recording system utilizing a transfer medium such as an intermediate transfer medium.
2. Description of the Related Art
In a recording method and apparatus, such as an ink jet recording system, that performs recording by jetting multi-color liquid in the form of droplets onto a recording medium in accordance with image signals, it is important to reproduce an image with little bleeding on a recording medium such as plain paper or wood free paper. In view of this, there have been many inventions relating to the recording method and apparatus. Examples of the prior art include the following three types.
1) A method in which an ink is dropped onto a recording medium, and an ink hardening is dropped onto the same spots on the recording medium at the same time as or before/after the ink dropping.
Japanese Laid-Open Patent Application Nos. 6-92009 and 6-92010 each disclose a method in which, when an ink is dropped onto a recording medium, or before/after that, an ink hardening agent is dropped onto the same spots on the recording medium, so that ink bleeding on the recording medium is prevented. However, in accordance with either invention, it is necessary to employ a special dropping unit for the ink hardening agent. Also, the ink hardening time makes the entire recording time longer than normal.
2) A method in which a material for reducing ink bleeding is applied to a recording medium in advance, and the material is fixed onto the recording sheet after the recording.
Japanese Laid-Open Patent Application No. 5-96720 discloses a method in which particles for reducing ink bleeding are applied to plain paper as a recording medium in advance, and the particles are fixed on to the paper after the ink fixing. However, the particles used in this invention dissolve with the ink. As a result, after the fixing, the particles might dissolve with the water or oil that is the solvent of the ink, causing ink bleeding on the recording medium. In view of this, this method is not good enough to maintain stability after the recording.
3) A method in which a transfer medium is employed, and an image is transferred from the transfer medium to a recording sheet after the viscosity of the ink is increased.
Japanese Laid-Open Patent Application No. 7-89067 discloses a so-called transfer-type ink jet recording apparatus. In this recording apparatus, an ink image is temporarily formed on an intermediate transfer medium. After the viscosity of the ink is increased to a desired degree, the image is transferred to a recording medium, so that problems such as ink bleeding can be avoided. However, in accordance with the invention, a surface active agent is applied to the transfer medium so as to improve the wettability. As a result, the ink requires a long time to increase its viscosity, and ink bleeding occurs not only on the transfer medium but also on the recording medium. Because of this, the recording apparatus is unsuitable for high-speed recording. Since the ink bleeding is worse in a solid image, the recording speed of the recording apparatus is limited even if it is applied to a line printer for high-speed recording.
Meanwhile, the applicant has already suggested a recording method and apparatus (Japanese Laid-Open Patent Application No. 9-359208) to solve the problems of the prior art. In accordance with the invention, a material in the form of powder that dissolves and swells with liquid in advance and increases the viscosity of the liquid is applied to a transfer medium, and the liquid is jetted to the transfer medium in accordance with image signals. The image is then transferred from the transfer medium to a recording medium. Thus, with the recording method and apparatus of the invention by the present applicant, high-speed recording can be performed and excellent images can be obtained on a recording medium such as plain paper.
However, there are many types of images, such as characters, pictures, and a mixture of characters and pictures. Since the transfer efficiency and image quality vary with the type of image, it is difficult to obtain a satisfactory image by attaching a single layer of the material that dissolves or swells with liquid and increases the viscosity of the liquid to the transfer medium. In order to overcome this difficulty, more than two layers of the material should be attached to the transfer medium. However, it is extremely difficult to form more than two layers of the material uniformly and securely on the transfer medium. Also, since the image quality depends on the conditions of the layers formed on the transfer medium, it is necessary to control the conditions of the layers.
The recording method and apparatus disclosed in Japanese Laid-Open Patent Application 9-359208 also has a problem with the material attached to the transfer medium in advance. More specifically, the particles in the material can be easily charged due to the contact friction among themselves. As a result, the particles in the material agglomerate, making it difficult to apply the material uniformly to the transfer medium.
It is a general object of the present invention to provide recording methods and apparatuses in which the above-mentioned problems are eliminated.
A first specific object of the present invention is to provide a recording method and apparatus that easily enable the obtaining of images of various kinds that excel in water resistance and preservability.
A second specific object of the present invention is to provide a recording method and apparatus that enable the obtaining of excellent images by preventing cohesion among particles due to friction charge.
The above objects of the present invention are achieved by a recording method comprising the steps of:
preparing a material that is dissolved or swelled by a liquid in advance and increases the viscosity of the liquid, the material being uniformly formed on a transfer medium;
forming an image on the transfer medium by bringing the liquid into contact with the material; and
transferring the image from the transfer medium to a recording medium.
Since the material can be applied uniformly to a surface of the transfer unit, an excellent image can be obtained by the above method.
In the above method of the present invention, no friction is caused in the material prepared. Accordingly, more than two layers of the material can be uniformly and steadily maintained, and the condition of the surface of the material can be adjusted, so that an excellent image can be obtained.
The above objects of the present invention are also achieved by a recording apparatus comprising:
a material preparing unit that prepares a material that is dissolved or swelled by liquid in advance and increases the viscosity of the liquid;
an image forming unit that forms an image on a transfer medium by bringing the liquid into contact with the material; and
a transfer unit that transfers the image from the transfer medium to a recording medium, wherein
the material preparing unit constitutes a material uniformly-applying unit that uniformly applies the material to the transfer medium.
With the above recording apparatus, the material can be formed uniformly on the transfer medium, so that an excellent image can be obtained.
In this recording apparatus, the material uniformly-applying unit constitutes a contact unit that is brought into contact with the material formed on the transfer medium without causing friction. Accordingly, more than two layers of the material can be uniformly and steadily maintained, and the condition of the surface of the material can be adjusted so as to obtain an excellent image.
Also in the recording apparatus of the present invention, the contact unit has a surface that is smoother than the surface of the material formed on the transfer medium. Accordingly, the layers of the material can be uniform.
In the recording apparatus of the present invention, the surface of the contact unit has regular concavities and convexities. Accordingly, it is possible to prevent removal caused by the materials solidified into layers or cohering due to friction charge. Thus, an excellent image can be obtained.
The recording apparatus of the present invention further comprises a driving unit that moves the surface of the material formed on the transfer medium and the surface of the contact unit at the same speed. Accordingly, no friction is caused in the material on the transfer medium, and the material can be uniformly and steadily fixed to the transfer medium. Thus, an excellent image can be obtained.
In the recording apparatus of the present invention, the contact unit constitutes a rotative unit that rotates in synchronization with the surface of the material formed on the transfer medium. Accordingly, no friction is caused in the material easily formed on the transfer medium, so that an excellent image can be obtained.
Also in the recording apparatus of the present invention, the contact unit further produces a material that is dissolved or swelled by liquid and increases the viscosity of the liquid on the material already formed on the transfer medium. Accordingly, the contact unit serves not only to even and regulate the material already adhering to the transfer medium, but also to apply the material to portions on the surface of the transfer medium not having the material formed thereon.
The above objects of the present invention are also achieved by a recording method comprising the steps of:
preparing a material that is dissolved or swelled by liquid in advance and increases the viscosity of the liquid on a transfer medium, the material being a conductive material;
forming an image on the transfer medium by bringing the liquid into contact with the material; and
transferring the image from the transfer medium to a recording medium.
Since the material is a conductive material in this method, a decrease in fluidity due to cohesion among the particles in the material caused by friction charge can be prevented. Accordingly, the material can be uniformly applied onto the surface of the transfer medium, and an excellent image can be repeatedly obtained.
In the above recording method of the present invention, the conductive material is a sodium salt of poly(acrylic acid), a salt of poly(acrylic acid) and aliphatic amine, or the salts containing a conductive powder at a given weight ratio. Accordingly, a decrease in fluidity due to cohesion among the particles in the material caused by friction charge can be prevented. Thus, the material can be applied uniformly to the transfer medium, and an excellent image can be repeatedly obtained.
Also in the recording method of the present invention, the step of preparing the material includes the steps of: holding the conductive material; and creating an electric potential difference between the conductive material and the transfer medium when the conductive material is transferred to the transfer medium. Accordingly, the material made up of conductive particles can be easily and uniformly applied to the surface of the transfer medium.
In the recording method of the present invention, the step of holding the conductive material includes a step of injecting an electric charge into the conductive material. Accordingly, the charged material made up of conductive particles can be easily and uniformly applied to the surface of the transfer medium.
Also in the recording method of the present invention, the step of creating the potential difference includes the step of electrifying the transfer medium. Accordingly, the material made up of conductive particles can be easily and uniformly applied to the surface of the transfer medium.
The above objects of the present invention are also achieved by a recording apparatus comprising:
a material preparing unit that prepares a material that is dissolved or swelled by liquid in advance and increases the viscosity of the liquid on a transfer medium, the material being a conductive material;
an image forming unit that forms an image on the transfer medium by bringing the liquid into contact with the material;
a transfer unit that transfers the image from the transfer medium to a recording medium;
a conductive material holding unit that holds the conductive material;
an electrode unit that sandwiches the transfer medium with the conductive material holding unit, and is situated opposite to the surface to which the material is transferred; and
a potential difference creating unit that creates a potential difference between the conductive material holding unit and the electrode unit.
With the above recording apparatus of the present invention, the material made up of conductive particles can be easily and uniformly applied to the surface of the transfer medium.
In the recording apparatus of the present invention, the conductive material holding unit is constituted by an elastic member. Accordingly, the contact area between the conductive material holding unit and the transfer medium becomes larger, so that the conductive particles can be uniformly and steadily applied to the surface of the transfer medium.
In the recording apparatus of the present invention, the elastic member is a urethane rubber roller, a silicone rubber roller, or a silicone sponge roller. Accordingly, the conductive particles can be more uniformly and steadily applied to the surface of the transfer medium.
The above objects of the present invention are also achieved by a recording apparatus comprising:
a material preparing unit that prepares a material that is dissolved or swelled by liquid in advance and increases the viscosity of the liquid in a transfer medium, the material being a conductive material;
an image forming unit that forms an image on the transfer medium by bringing the liquid into contact with the material;
a transfer unit that transfers the image from the transfer medium to a recording medium;
a conductive material holding unit that holds the conductive material;
a first charging unit that charges the conductive material holding unit;
a second charging unit that charges a surface of the transfer medium; and
a material affixing unit that affixes the conductive material to the surface of the transfer medium by means of an electric charge injected into the conductive material by the conductive material holding unit.
With this recording apparatus of the present invention, the conductive particles can be easily and uniformly applied to the surface of the transfer medium.
In the recording apparatus of the present invention, the material affixing unit also serves as a transfer unit that transfers the conductive material. Accordingly, the conductive particles can be more easily and uniformly applied to the surface of the transfer medium.
Other objects and further features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.